| HLA | histocompatibility leukocyte antigen; histocompatibility locus antigen; homologous leukocyte antibod... |
|---|---|
| TLA | thymus leukemia antigen; tissue lactase activity; tongue-to-lip adhesion; translaryngeal aspiration;... |
| TSA | technical surgical assistance; toluene sulfonic acid; total shoulder arthroplasty; total solute abso... |
| TSTA | toxoplasmin skin test antigen; tumor-specific tissue antigen; tumor-specific transplantation antigen... |
| BAIF | bile acid independent flow |
| thymus and parathyroids, hypoplasia of | See third and fourth pharyngeal pouch syndrome. (12 Dec 1998) |
|---|---|
| thymus-dependent zone | <anatomy> Mid cortical region of lymph node, area that is particularly depleted of T lymphocytes in thymectomised animals and is referred to as the thymus dependent area. (18 Nov 1997) |
| thymus derived lymphocyte | <haematology, immunology> A class of lymphocytes, so called because they are derived from the thymus and have been through thymic processing. Involved primarily in controlling cell-mediated immune reactions and in the control of B-cell development. The T-cells coordinate the immune system by secreting lymphokine hormones. There are 3 fundamentally different types of t cells : helper, killer, and suppressor. Each has many subdivisions. T-cells are also called t lymphocytes. They bear T-cell antigen receptors (CD3) and lack Fc or C3b receptors. Major T-cell subsets are CD4 (mainly helper cells) and CD8 (mostly cytotoxic or suppressor T-cells). Uncontrolled proliferation of this type of cell gives rise to T-cell leukaemia/lymphoma. (21 Jun 1999) |
| thymus extracts | Extracts of the thymus that contain specific, but uncharacterised factors or proteins with specific activities; three distinct substances are already known: thymotoxin, thymin and thymosin. (12 Dec 1998) |
| thymus gland | A bilaterally symmetric lymphoid organ situated in the anterior superior mediastinum. Each of its two lobes consists of an outer zone, the cortex, relatively rich in lymphocytes (thymocytes), and an inner zone, the medulla, relatively rich in epithelial cells. The thymus is the site of the production of T-lymphocytes. The thymus reaches its maximal development at about puberty and then undergoes a gradual process of involution resulting in a slow decline of immune function throughout adulthood. (12 Dec 1998) |
| thymus hormones | Humoral factors secreted by the thymus gland. They participate in the development of the lymphoid system and the maturation of the cellular immune response. (12 Dec 1998) |
| thymus hyperplasia | Enlargement of the thymus. A condition described in the late 1940's and 1950's as pathological thymic hypertrophy was status thymolymphaticus and was treated with radiotherapy. Unnecessary removal of the thymus was also practiced. It later became apparent that the thymus undergoes normal physiological hypertrophy, reaching a maximum at puberty and involuting thereafter. The concept of status thymolymphaticus has been abandoned. Thymus hyperplasia is present in two thirds of all patients with myasthenia gravis. (12 Dec 1998) |
| thymus treatment | Treatment of disease by administration of extracts of thymus gland. (05 Mar 2000) |
| lobules of thymus | Areas of thymic tissue 0.5 to 2 mm in diameter with a cortex and medulla. Synonym: lobuli thymi. (05 Mar 2000) |
| acetone-insoluble antigen | A diphosphatidyl glycerol that is found in the membrane of Treponema pallidum and is the antigen detected by the Wasserman test for syphilis. (18 Nov 1997) |
| allogeneic antigen | Genetic variations of the same antigens within a given species. (05 Mar 2000) |
| antigen | Virus coded cell surface antigens that appear soon after the infection of a cell by virus, but before virus replication has begun. See: early gene. (18 Nov 1997) |
| antigen-antibody complex | The complex formed by the binding of antigen and antibody molecules. The deposition of large antigen-antibody complexes leading to tissue damage causes immune complex diseases. If the antigen is polyvalent the complex may be insoluble. Immune complexes activate complement through the classical pathway. See: glomerulonephritis, Arthus reaction, type III hypersensitivity. (12 Dec 1998) |
| antigen-antibody reaction | The phenomenon, occurring in vitro or in vivo, of antibody combining with antigen of the type that stimulated the formation of the antibody, thereby resulting in agglutination, precipitation, complement fixation, greater susceptibility to ingestion and destruction by phagocytes, or neutralization of exotoxin. See: skin test. (05 Mar 2000) |
| antigen-binding site | <immunology> In immune network theory, an idiotope, an antigenic site of an antibody that is responsible for that antibody binding to an antigenic determinant (epitope). Also used of the site on a ligand molecule to which a cell surface receptor binds. (18 Nov 1997) |